Robust radio resource control signaling for HSDPA

Abstract

A radio network controller is operable in both a unicast signaling mode and a bi-cast signaling mode. In unicast signaling mode, the radio network controller is operable to send radio resource control signals to a mobile station through a serving cell. The radio network controller is operable to go into bi-cast signaling mode during a hard handover. In the bi-cast signaling mode, the radio network controller is operable to send radio resource control messages to the mobile station through both the current serving cell and a target cell. The mobile station is configured to listen to both the current serving cell and the target cell for radio resource control messages. User data, however, is transmitted only from the current serving cell to the mobile station.

What is claimed is: 
     
       1. A signaling method implemented by a radio network controller for executing a hard handover of a mobile station receiving packet data on a shared downlink traffic channel, said method comprising:
 initiating a hard handover of said mobile station from a current serving cell to a target cell responsive to a signaling message from said mobile station; 
 bi-casting radio resource control messages to said mobile station through both said current serving cell and said target cell during said handover; and 
 uni-casting user data to said mobile station through the current serving cell during said handover. 
 
     
     
       2. The signaling method of  claim 1  wherein said signaling message comprises a handover request. 
     
     
       3. The signaling method of  claim 1  wherein said signaling message comprises a signal strength measurement report. 
     
     
       4. The signaling method of  claim 1  wherein bi-casting radio resource control messages comprises bi-casting a handover command to said mobile station through both said current serving cell and said target cell. 
     
     
       5. The signaling method of  claim 1  wherein bi-casting radio resource control messages comprises transmitting said radio resource control messages to said mobile station in band over said shared downlink traffic channel from both said current serving cell and said target cell. 
     
     
       6. The signaling method of  claim 5  wherein said shared downlink traffic channel comprises a High Speed Downlink Shared Channel, HS-DSCH, in a Wideband Code Division Multiple Access, WCDMA, system. 
     
     
       7. A radio network controller for a radio access network, said radio network controller comprising a radio resource controller operative to:
 initiate a hard handover from a current serving cell to a target cell responsive to a signaling message from a mobile station; 
 bi-cast radio resource control messages to said mobile station through both said current serving cell and said target cell during said handover; and 
 uni-cast user data to said mobile station through the current serving cell during said handover. 
 
     
     
       8. The radio network controller of  claim 7  wherein said signaling message comprises a handover request from said mobile station. 
     
     
       9. The radio network controller of  claim 7  wherein said signaling message comprises a signal strength measurement report from the mobile station. 
     
     
       10. The radio network controller of  claim 7  wherein the radio resource control messages bi-cast to the mobile station through said current serving cell and said target cell include acknowledgement of a handover request. 
     
     
       11. The radio network controller of  claim 7  wherein said radio network controller is operative to bi-cast radio resource control messages to said mobile station in band over a shared downlink traffic channel from both said current serving cell and said target cell. 
     
     
       12. The radio network controller of  claim 11  wherein said shared downlink traffic channel comprises a High Speed Downlink Shared Channel, HS-DSCH, in a Wideband Code Division Multiple Access, WCDMA, system. 
     
     
       13. A signaling method implemented by a mobile station for executing a handover in a mobile communication network, said method comprising:
 sending a signaling message to a radio network controller to initiate a hard handover from a current serving cell to a target cell; and 
 listening on a downlink channel in both said current serving cell and said target cell for a response message to said signaling message, wherein the response message is bi-cast in both the current serving cell and the target cell. 
 
     
     
       14. The signaling method of  claim 13  wherein the signaling message sent by said mobile station to initiate the hard handover comprises a handover request. 
     
     
       15. The signaling method of  claim 13  wherein the signaling message sent by said mobile station to initiate the hard handover comprises a signal strength measurement report. 
     
     
       16. The signaling method of  claim 13  wherein listening on a downlink channel in both said current serving cell and target cell for a response message comprises listening to a control channel for both said current serving cell and said target cell. 
     
     
       17. The signaling method of  claim 16  further comprising listening to said control channel for both said current serving cell and said target cell to detect a scheduled transmission of said response message on a shared downlink traffic channel. 
     
     
       18. The signaling method of  claim 17  further comprising receiving said response message in band over said shared downlink traffic channel. 
     
     
       19. The signaling method of  claim 18  wherein said shared downlink traffic channel comprises a High Speed Downlink Shared Channel, HS-DSCH, in a Wideband Code Division Multiple Access, WCDMA, system. 
     
     
       20. The signaling method of  claim 13  further comprising sending a confirmation message to said radio network controller upon receipt of said response message. 
     
     
       21. A mobile station capable of receiving data on a shared downlink traffic channel, said mobile station comprising:
 a transceiver to transmit and receive data, including radio resource control messages; and a control unit to control said transceiver, said transceiver configured to: 
 send a signaling message to a radio network controller to initiate a hard handover from a current serving cell to a target cell; and 
 listen for a response message to said signaling message from said radio network controller on a downlink channel in both said current serving cell and said target cell, wherein the response message is bi-cast in both the current serving cell and the target cell. 
 
     
     
       22. The mobile station of  claim 21  wherein the control unit is configured to send a handover request to the radio network controller to initiate the hard handover. 
     
     
       23. The mobile station of  claim 21  wherein the control unit is configured to send a signal strength measurement report to the radio network controller to initiate the hard handover. 
     
     
       24. The mobile station of  claim 21  wherein the control unit is configured to listen on a downlink control channel for both said current serving cell and said target cell for said response message. 
     
     
       25. The mobile station of  claim 24  wherein the control unit is configured to listen on said downlink control channel for both said current serving cell and said target cell for a scheduled transmission of said response message on a shared downlink traffic channel. 
     
     
       26. The mobile station of  claim 25  wherein the mobile station is configured to receive the response message over the shared downlink traffic channel. 
     
     
       27. The mobile station of  claim 25  wherein the control unit sends a confirmation message to said radio network controller upon receipt of said response message. 
     
     
       28. A non-transitory computer readable medium storing code for controlling a mobile station, said code including:
 code for causing the mobile station to send a signaling message to a radio resource controller to request a hard handover from a current serving cell to a target cell; 
 code for causing the mobile station to listen in both said current serving cell and said target cell for a response to said signaling message, wherein the response message is bi-cast in both the current serving cell and the target cell. 
 
     
     
       29. The computer readable medium of  claim 28  wherein the code for causing the mobile station to listen in both said current serving cell and said target cell for a response to said signaling message causes the mobile station to listen on a control channel in both said current serving cell and said target cell. 
     
     
       30. The computer readable medium of  claim 29  wherein the code for causing the mobile station to listen in both said current serving cell and said target cell for a response to said signaling message causes the mobile station to listen to said control channel for a scheduled transmission of said response message on a shared downlink traffic channel. 
     
     
       31. A non-transitory computer readable medium storing code for controlling a radio network controller, said code including:
 code for causing the radio network controller to initiate a hard handover of a mobile station from a current serving cell to a target cell responsive to a signaling message from said mobile station; 
 code for causing the radio network controller to bi-cast a radio resource control messages to said mobile station through both said current serving cell and said target cell during said handover; 
 code for causing the radio network controller to uni-cast user data to said mobile station through the current serving cell during said handover. 
 
     
     
       32. The computer readable medium of  claim 31  wherein the code for causing the radio network controller to bi-cast radio resource control messages through both said current serving cell and said target cell during said handover causes the radio network controller to bi-cast radio resource control messages using a shared downlink traffic channels in the current serving cell and the target cell.